Tankless gas vs. electric water heater- pros/cons

gbwillner

I know there are a lot of posts on the subject, I haven't been able to decide which one to go with for my planned finished basement. I am requesting advice. The upgrade won't come right away, but I need to update the electrical and my decision rests on which one I will get.

I currently have a 2000 sq ft, 2 story solid masonry home, and am in the middle of a basement renovation that will add about 900 sq ft to the house. My wiring is original and I have a 100 Amp service box that is Federal Pacific and needs to be changed. I only have 1 full bath currently but will be adding another, plus a half bath (2 full/2 half when done with renovations). I am in St. Louis, MO, with water temp coming in at 55 degrees.

I know until recently no one would have recommended electric tankless for whole house applications, but there is one- Steibel Eltron Tempra 36, that seems suitable for my use http://www.amazon.com/Stiebel-Eltron...5181012&sr=1-1 . The major downside is having to upgrade to a 400 A service, which would normally kill a deal but I need to upgrade service anyway. The question is to upgrade to a 200 A service and get a gas tankless (probably a Bosch http://www.amazon.com/Bosch-ProTankl...=2IBPX10ARXSTK ) or the 400 A service and get the electric.

Pros for electric-
I can install it myself- relatively easily (save install costs ($1000?))
Smaller/compact, does not need to be vented, can be placed anywhere
cheaper to buy (almost $1000)
Does not need to be serviced as often (lose risking warranty)


Pros for gas-
more efficient, may get money back long term
tax rebate.. maybe (may reach limit with A/C purchase)
save on electrical upgrade (almost $1000- won't need 400 A service)
Been around longer, may be easier to get serviced

Any advice? THX

Bondo

Ayuh,... 400amps,..?? How much does that thing draw,..??
I installed a Bosch electric,+ it draws 80amps(2, 40amp legs)...
Granted,.. You don't want the electric stove,+ the dryer,+ the waterheater on at the same time, but it's running Fine on a 200amp service...

gbwillner

It draws up to 150 A on a 240 V circuit and takes 3 breakers! On the flip side it also heats up a lot of water, raising the temp of incoming water 55 degrees at 4.5 GPM. Not nearly as good as the gas one I linked but enough to run two showers at the same time on the coldest day of the year at 110 degrees.

Bondo

Ayuh,... So this is an Apples,+ Oranges comparision,..??

gbwillner

Not really- This is as good as electric gets and it is adequate for my use, but obviously not as good as the gas system. But it is also cheaper and easier to install, where I could do it myself. I guess the question would be, should I go with an apple or an orange given that I want a piece of fruit?

Obviously if money was no object I would go with gas... but it would likely cost more than $1000 more for the system.

plumberbob

GAS-FIRED OR ELECTRIC? WHAT IS BEST FOR MY NEEDS?



Every day someone contacts our company asking us for an electric tankless water heater. What we notice is one common misconception. Almost everyone inquiring about an electric tankless heater wants to install it as a replacement for an existing electric tank-type water heater. We have found that most people are visualizing that they simply mount the new electric tankless heater on the wall and plug it into the pre-existing wiring from their old tank type heater. This is simply not a correct assumption. For an electric tankless heater to supply hot water at the required GPM (Gallons Per Minute), a much larger amount of electricity is required. The amount of electricity required is huge when compared to typical appliances. In fact, an electric tankless hot water heater’s electricity requirements exceed the capacity of the typical American home. To find out the details, please read this report and comparison. We have taken the time to explain these energy consumption needs in an easy to understand way.

Early in our research, we extensively evaluated electric tankless water heater technology and chose to focus our efforts on gas-fired models. We decided that our company would not enter into the business of electric tankless heaters for a number of reasons. Without turning this article into a sales pitch, we will point out some of the same facts that resulted in our company’s selection of gas fired heaters as our product line.
Simply comparing our popular EZ DELUXE 4.0 GPM model to a similar but slightly smaller GPM capacity electric unit, one can clearly see the differences. (To be fair, we compare our EZ Deluxe to one slightly smaller and one slightly larger electric powered unit. The manufacturer’s specifications of the models used in this comparison are listed on their web site and we presume that they are accurate. However, we did not conduct tests on the specific electric models used in this specification comparison.)

This complete article is available at http://www.eztankless.com/Gas_vs_Electric.html

gbwillner

Thanks for the advice from everyone- here are my experiences:

I ended up installing the Bosch Gas heater I mentioned, and I am glad I did. I was actually able to install it myself, which required increasing the inlet gas lines to 1" to the unit.

My reasoning was actually simple after I had the electricians come and bid on the electrical job. They were asking $2k to upgrade from my 100A service to 200A, but more than $4K (and upwards of $6K) for a 300-400A service. This pretty much wiped out any financial incentive I would have for the electrical heater.

But What I find to be the biggest plus was how variable the GPMs are on these devices. Assuming you can pull all the required gas for optimal performance, and assuming you can find true estimates of the ground water temp., you will see how quickly you can use up all the GPMs of these devices. I found that in the dead of winter the Bosch heater was using roughly 80-90% power running the shower, kitchen sink, and two small bathroom sinks- that should be roughly 5-6GPM- and only raising the temp 55deg to 125 deg. Theoretically I should not have been using that much power (should theoretically get something like 10 GPM), but it is likely my ground water temp is much colder than that. Bottom line is that there is NO WAY I could be using all those water sources with the electric water heater and the same conditions.